The objectives of the study are to (1) determine the efficacy and dose-response of methylphenidate treatment of attention problems after pediatric traumatic brain injury (TBI) and (2) provide a better understanding of the relationship of a prior history of attention deficit hyperactivity disorder (ADHD), ADHD subtypes after TBI, executive function, and attentional control to treatment efficacy. The proposed clinical trial will enroll 50 children, age 6-17 years, with attention problems >6 months after moderate to severe TBI into a randomized, double-blind, placebo-controlled, cross-over design trial with 3 dose conditions (low, medium, and high).